In general mass spectrometry, as a method of scanning a mass-to-charge ratio m/z of a mass selection-separation target, the following two types are mainly exemplified. Here, m is ion mass, and z is a charge number of an ion. A first type is a method of controlling values of a direct current voltage U and amplitude V of a radio-frequency voltage (RF voltage), which are applied to four or more rod electrodes, to be proportional to a mass-to-charge ratio m/z of a mass selection-separation target. A second type is a method of controlling a value of an angular frequency Ω of the radio-frequency voltage (RF voltage), which is applied to four or more rod electrodes, to be proportional to 1/√m/z. As the latter method, a method of controlling the radio-frequency voltage (RF voltage) to be a high frequency when an ion has low mass number and to be a low frequency when an ion has high mass number is disclosed in PTL 1.